Leaking shed roof at transition from garage

I've been chasing a leak for over a year now on my machine shed. This entire thing was clearly an afterthought at some point in the past, added on to the garage. Its been leaking for a long time and now IM the lucky guy who gets to deal with it.

My initial suspect was the foam between metal roof and flashing due to poor install and dry rot over time. Then I found one of the seams in the flashing was funneling water IN not out. I "fixed" both with tar last fall. Worked great for a few months, but now Im finding the tar has cracked because I spread it way too thin.

At this point Im considering what the best approach is while staying on a budget.
Continue to patch it and hope for the best? Maybe try to form a thick bead of tar across that whole seam.
Buy a 50' roll of extra wide flashing? Rip the old flashing out entirely. I bet forming a 28ft long piece to the shape I need by hand would really suck..
Buy some preformed 90 degree 6"x6" and tuck it up under the existing?

If anyone is a roofer by trade or ever dealt with the transition to such a shallow pitch Id welcome any ideas!




Initial repair thinking the foam between ribs was the culprit (because it was missing in areas)



Very hard to see wet, but its way too thin along the edge of the flashing and forming cracks

 

Also just to add - yes I know the entire roof, sheathing and probably even some 2x6s need to be ripped off and replaced entirely.

But funds are short right now. Short term Im just trying to keep it dry and buy myself a few years before doing the whole roof

 

A stop gap (not a roofer here) would be wider flashing or gutter away - IE taking the water away from the joint

Yeah that wood looks really bad, but you of course see and smell that.

 

The wet patch material typically expects a fiberglass cloth or repair fabric to be used underneath.. otherwise temperature changes and UV will cause cracking as you've experienced.

Also.. water can track the craziest paths sometimes.. check at the top of the flashing where the shingles meet.. you may be looking at the wrong spot. cover way more of the area than you think necessary. I maintain a flat roof old building and it's a MFer. Good luck.

 

Tar products only last a season at best, they all crack.

A longer term patch is a urethane product, that stuff is tough and will hold up to the sun much longer. Sorry, it will be a better job if you dig the tar out.

Anything you can do to direct the water away from the joint will help as well.

 

The 'good' wetpatch stuff is over $55 for 5 gallons and repair tape is overpriced... AND it's a shitty band-aid. Take a generous swipe at it then please don't spend any more energy or money on it. It's a losing battle. Cut out the rot, seal it up correctly and enjoy for decades.

 

lol I read that in the instructions on the bucket. Thought to myself, nahh I can use the existing foam as a backer in most areas. Oh well live and learn

That was my thought as well with wider flashing. Just a matter of getting it bent to shape..

 

If you go to a metal roofing products dealer - not a box store - they have a catalog of ready made wall flashing & such.

They cost less than you would think and usually deliver in a week or two.

 

the best leak-prevention is to not allow water to sit on the problem. i'd install a gutter at the transition to catch the majority of the shingled roofs runoff, and direct it to a far safer location for run off, and it would also act as an 'umbrella' over the seam, further keeping it dryer.

 

So you're saying take the existing flashing off entirely then add a gutter? Im not sure I have room for that. I can take a measurement tonight but I doubt if theres much more than 5" from the edge of the shingles to the ribs of the metal.

Also how do I keep water from running uphill? Sounds dumb, but I get a lot of storms out of the SW here. Heavy winds sweep right up that metal roof.

 

Thanks. Ill have to look around for such a place in this area

 

Ask at a local sawmill if you have one around, they work with people building barns & such and can source the metal or at least direct you.

 

You don't. Metal roof manufactures have a minimum pitch requirement for their roofs. It looks like yours is nearly flat. The correct options are tear it off and increase the pitch if staying with metal, or use a product made for a flat roof, like some of the rolled sheet roofing.

 

....yeah, typically anything less than a 3-12 pitch, roll material is a a better option, though that having been said, and knowing we are on a budget and trying to stop the bleeding, so to speak, the limited length of the transition to the corrugated metal catches my attention.

...were I trying to 'band aid it, first, I'd get some additional overlap over the top of the metal roof section to extend that gable roof water run off further beyond that seam, and i'd undo the upper most fasteners to slid it in there, and then re-secure it. ...even a roll of inexpensive coil type material would probably provide a lot of relief, and wouldn't look like shit like that tar.....

 

haha yeah I know, like I said this entire thing was definitely an afterthought by a previous "DIY" owner.

Thanks. Im leaning towards that idea myself. Based on @RustyGreens idea I found a little shop in the greater area that advertises custom metal roofs with a full fab shop. Im betting they could bend me some 10ft sections of flashing with the right angle. A full 4-5" up under the existing flashing and a nice generous length flat extending over the corrugated metal roof

 

I took a measurement last night. Definitely no room for gutters.

Also I measured the pitch for shits and grins. Not even 1:12. Only 3.5 inch rise over my 4 foot level

 

That shop got back to me - $1200 for a 28 ft "custom transition"

Not sure they understood what I want, nor did they want the work with that price.

In any case planning to pick up a 50 ft roll of 10" flashing and bend my own. Thinking Ill sandwich the top ~3" between two 2x4s in the vice. Use that as a guide with a rubber mallet to bend the angle I need. Never worked with roll flashing before but Id hope that will give me a nice clean bend.

Do you guys think 7" overlap over the corrugated metal will be enough? I can also get 14" valley flashing locally. But only in 10 ft rolls

 

$1200 !

Look here: https://midmainemetal.com/trims/

I was thinking something like this.



They are 10' sections but no problem to overlap and use some urethane sealer on.

 

Hmm they are only a few hours from me. #6 looks like it could just work. Ill have to check them out

 

You can also buy the foam closers that go on top of the roof and under the flashing. Just need to know the profile of your corrugations as there are different styles.